RESUMO
Objective To explore the mechanism of tetramethylpyrazine (TMP) in preventing and treating inflammation and cell apoptosis in rats. Methods Totally 180 healthy male SD rats were selected and randomly divided into sham operation group (sham), cerebral ischemia reperfusion injury(CIRI) group, nimodipine group (nimodipine, N), and TMP subdivided into low-dose group (low). There were three subgroups: low-dose(L), medium dose (M), and high dose (H). In CIRI group a modified suture method was used to prepare the CIRI model; each TMP group was given tail injection 30 minutes before surgery. Intervention was given by intravenous injection of 5 mg/kg, 10 mg/kg, and 30 mg/kg TMP. N group was given tail vein injection of nimodipine (1 mg/kg), sham group and CIRI group were given the same dose of normal saline. SD rats in each group were scored for neurological deficits immediately after the CIRI model was constructed. At the same time, after 24 hours of reperfusion in each group,2,3,5-triphenyltetrazole chloride (TTC) staining, HE staining and Nissl staining were performed to detect the morphological changes of the parietal cortex ischemic penumbra; ELISA to detect the expression of IL-1β and IL-8 in the parietal cortex, TUNEL detects neuronal cell apoptosis in the parietal cortex, immunofluorescence detected the expression of β-catenin positive cells in the parietal cortex, and Western blotting detected the expression of Bax and Bcl-2 in the parietal cortex. Results Compared with the sham group, the neurological deficit score in the CIRI group was significantly higher(P<0.01). The HE and Nissl staining showed neuronal swelling and degeneration, some of which showed vacuole-like changes, pyknosis and deep staining of the nucleus, and a decrease in the number of neurons(P<0.01), the number of Nissl bodies was significantly reduced(P<0.01);the concentrations of inflammatory factors IL-1β and IL-8 increased significantly(P<0.01), apoptotic cells and β-catenin-positive cells and their average absorbance values both increased significantly(P<0.01);the expression of Bcl-2 protein decreased, while the expression of Bax protein increased significantly(P<0.01). Compared with the CIRI group, the neurological deficit scores of the rats in the N group and the TMP intervention group were reduced (P<0.01), HE and Nissl staining revealed that the edema of large neurons was reduced, a few nerve cells were destroyed, and the number of neurons increased(P<0.01), the number of Nissl bodies ncreased (P<0.01);the concentration of inflammatory factors IL-1β and IL-8 decreased significantly(P<0.01), apoptotic cells and β-catenin-positive cells and the average absorbance value decreased significantly (P<0.01)the expression of Bcl-2 protein increased, while the expression of Bax protein decreased significantly(P<0.01);compared with group N, as the concentration of TMP increased, nerve function, inflammatory response, and neuronal pathological changes showed dose-effects relationship (P<0.05). Conclusion TMP intervention treatment can alleviate the neurological deficit, neuronal damage, tissue edema, inflammatory factors and cell apoptosis after CIRI in rats. The mechanism may be related to the inhibition of the expression of β-catenin protein in the parietal cortex of rats.